Sulfonation of saturated fatty acid esters of polyvalent alcohols



INVENTORS W. SULFONATION OF SATURATED FATTY ACID ESTERS OF POLYVALENTALCOHOLS WERNER STE/N HERBERT WEISS OTTO KOCH J n k t 4 a k Al T T T w u1 l di m 1 Q h 1- i Q m T L II n i l T 9 Q 3 H 1 kl 8 .1 Q Q.\ I 5 q i 3k\ .9

May 17, 1966 Filed May 15, 1962 y 17, 1966 w. STEIN ETAL 3,251,868

7 SULFONATION OF SATURATED FATTY ACID ESTERS OF POLYVALENT ALCOHOLSvFiled May 15, 1962 4 2 Sheets-Sheet 2 INVENTORS F3 5 WERNER STE/NHERBERT WE/SS OTTO KOCH United States Patent 3,251 868 SULFONATIQN OFSATI JRATED FATTY ACID ESTERS 0F POLYVALENT ALCOHOLS Werner Stein,Duesseldorf-Holthausen, Herbert Weiss,

14 Claims. 1260-400 This invention relates to new and usefulimprovements in the sulfonation of fatty acid esters of polyvalentalcohols. The invention more particularly relates to an improvedprocedure for allowing a trouble-free sulfonation of esters of fattyacids and polyvalent alcohols, particularly fatty acid triglyceridesinto the corresponding alpha sulfonic acids using gaseous sulfurtrioxide.

It is well known to convert the fatty acid esters of polyvalentalcohols, such as fatty acid triglycerides into the corresponding alphasulfonic acids by a sulfonation reaction. For this purpose, liquidsulfur dioxide or sulfur dioxide dissolved in solvents has been used asthe sulfonation agent. While the use of an excess quantity of gaseoussulfur trioxide, preferably diluted ,with inert gases, has provenpractical as a sulfonation agent for other materials, such as fattyacids, the use of this sulfonation agent has not proven practical inconnection with the fatty acid esters of polyvalent alcoholsparticularly of triglycerides as when sulfonating these materials withthe sulfur trioxide gas, the viscosity of the reaction mixture increasesto a point where further handling becomes diflicult if not impossibleand the gas stream containing the sulfouating agent produces enormousquantities of an uncontrollable foam which interferes with the reaction.

One object of this invention is the sulfonation of fatty acid esters ofpolyvalent alcohols, such as fatty acid triglycen'des, using an excessof gaseous sulfur trioxide as the sulfonation agent, without theabove-mentioned difficulties.

This and still further objects will become apparent from the followingdescription read in conjunction with the drawings in which:

FIG. 1 diagrammatically shows an embodiment of a reaction vessel foreffecting the sulfonation in accordance with the invention, and

FIG. 2 diagrammatically shows a further embodiment of an apparatus foreffecting the sulfonation in accordance with the invention. 7

In accordance with the invention, it has now surprisingly been foundthat the prior art difiicu'lties encountered in connection with thesulfonation of fatty acid esters of polyvalent alcohols using gaseoussulfur trioxide as the sulfonation agent and in particular theuncontrollable viscosity increase and foam formation may be avoided ifthe sulfonation is effected with the fatty acid esters of the polyvalentalcohols being anadmixture with fatty acids or their derivatives, suchas their esters with monova'lent alcohols or their nitriles.

As the starting material for carrying out of the process inaccordancewith the invention, it is preferable to use natural triglycerides thoughsynthetic triglycerides or synthetic esters of fatty acids with otherpolyvalent alcohols, such as for example glycols, pentaerythrite,mannite, sorbite, or the like may be used.

The fatty acid radicals present in both the fatty acid esters ofpolyvalent alcohols andfatty acids, fatty acid esters of monovalentalcohols or fatty acid nitriles, to be admixed therewith for thesulfonation in accordance with the invention, may be of any origin andshould contain 628 and preferably 8-18 carbon atoms. These fatty acidice radicals may, for example, some from the natural fats of plants,.land-or-Water-animals. Through selection of the starting fats, it ispossible to extensively influence the properties of the sulfonates to beproduced. Thus, from fats which preferably contain fatty acids with10-14 carbon atoms per fatty acid radical, particularly from the fats ofthe lauricacid group, which are rich in fatty acid with 12 carbon atoms,products which are readily soluble at lower temperatures of, for example20-'45 C. are obtained. From other fats, which preferably contain fattyacids with l6-l8 and more carbon atoms per fatty acid radical, forexample from other plant fats than the above named, from tallow or fromthe Whaleand dish-oils, there are obtained products which areparticularly useful at temperatures within the range of 50'100 C.

The materials present in the mixture sulfonated in accordance with theinvention should not contain further sulfatizable or sulfonatablegroups, apart from alpha-position hydrogen atoms, such as for exampledouble bonds or alcoholic hydroxyl groups.

The fatty acids, or their derivatives, i.e. the nitriles or esters withmonovalent alcohols, may be any such material having fatty acid radicalsas specified above. in connection, withthe fatty acid esters ofmonovalent alcohols to be processed in accordance with the invention,these alcohols may be of primary and secondary nature and contain 1-20carbons atoms in the molecule. Accordingly, for example, the esters offatty acids with methylto nonyl-alcohols are applicable though it isalso possible to use the fatty acid esters which contain radicals ofstill higher alcohols in the molecule as may be produced for examplethrough reduction from the initially mentioned fatty acids or fatty acidmixtures or in other ways synthetically. Ex

'amples of easily accessible esters of fatty acids with higherfat-alcohols include the hydrogenation products of the oleylolateoccurring in the sperm oil or the naturally occurring or syntheticallyproduced wax-esters.

Many fats, particularly such .of natural origin, and the fatty acids andtheir derivatives produced therefrom, often contain accompanyingsubstances which in the sulfonation produce strongly coloreddecomposition products. Although it is possible to later bleach thesedecomposition products according to a process referred to hereinafter,it is advisable not to burden the sulfonationand the bleaching-processby the presence of these accompanying substances and their decompositionproduct and to forthwith remove the same from the fats and/ or the fattyacids or their derivatives produced therefrom. To such products, whichcause upon the sulfonation, discoloration, belong, for example,unsaturated fatty acids or fatty acid derivatives. Therefore, thestarting fats to be processed should be, as far as possible, extensivelysaturated, i.e. have iodine numbers below 5, and preferably below 2.

If fatty acids are added to the starting materials to be sulfonated inaccordance with the invention, then distillates are preferably used asthe starting material, Which is also advisable in connection with thefatty acid derivatives sofar as these are distillable under thetechnical prerequisites in each case. If the starting materials are notinitially purified by distillation, on account of a high boiling pointor for other reasons may be distilled, as for example in triglycerides,then it is advisable to initially remove the impurities present in thestarting material to be sulfonated by other conventional methods. Thus,for example in the case of the natural fats and particularly the naturaltriglycerides, albuminous substances and slimy substances (mucins), areseparated by the deacidification and refining of the oils in a mannerknown per se.

In general, the benefits of addition of fatty acids and/ or fatty acidderivatives, in accordance with the invention, I

are already noticeable if their quantity amounts to 5 weight percent ofthe entire starting material. However, larger quantities are preferred,as for example at least 'and preferably 20-75 weight percent of fattyacid derivatives. In general, amounts of 85% fatty acid and/or fattyacid derivative will not be used.

Of the fatty acid derivatives, the esters of primary or secondaryalcohols, containing 1-5 carbon atoms, have proved particularlysuitable.

' The fatty acids or other fatty acid derivatives, to be sulfonated inmixture with fatty acid esters of polyvalent alcohols, may have achain-length-distribution of the fatty acid radicals which deviates fromthat of the esters of polyvalent alcohols, ,or which corresponds withit.

. The sulfonation may be carried out continuously or discontinuously, bybringing together the sulfur-trioxide, diluted with an inert gas, withthe starting material to be sulfonated. As inert gases, for example,air, nitrogen,

carbonic acid, etc. may be used. The sulfur-trioxide content shouldamount to 2-40 volume percent, preferably 3-20 volume percent of the gasmixture.

The sulfonation agent quantities to be used per mol of fatty acidradical lie within the range of 1.1-1.8, preferably of 1.2-1.6 molsulfur-trioxide, wherein with increasing length of the fatty acid-andalcohol-radical, greater sulfonation agent quantities are needed inorder to attain high degrees of sulfonation. The reaction sets in withpractically serviceable velocities at about 30 C. and is appropriatelycarried out at gradually rising temperature. degrees of sulfonation,temperatures of 70-100 C., preferably of 75-95' C. and particularly of80-90 C., are necessary. Since the quantity of the colored by-products,formed in the sulfonation, increases with rising temperature, it isadvisable to hold the reaction mixture for as short a time as possibleat the end temperature.

If one works in the interest of an extensive sulfonation at hightemperatures, then the formation of brownblack colored decompositionproducts may not be avoided. There are, however, two sulfonationprocesses, with the aid of which it is possible to obtain a high degreeof sulfonation with substantially decreased formation of the discoloreddecomposition products.

The one of these two processes. is described in co-pending applicationSerial No. 194,840 filed on the same day herewith and consists in addingto the starting material in a first sulfonation step at temperatures ofat most 70 C. not more than 65-90% of the sulfur-trioxid'e to be used,and then adding the residual sulfur-trioxide in a further sulfonationstep or steps at higher temperatures. It is preferable to work withrising temperature, wherein the reaction starts in the first step atabout 30 C. and preferably proceeds within the range of 40-65 C., and inthe second step is carried out at temperatures of 75-95 C., preferablyof 80-90 C. This process is particularly suitable for a continuouscarrying-out, wherein one passes the starting material to be sulfonatedthrough reaction zones,

in which the temperature rises from zone to zone while thesulfur-trioxide is added in amounts calculated as required for theprogressing reaction. These reaction zones may have the form of reactionvessels connected behind one another, in which an inert gas stream,containing sulfurtrioxide, is introduced into .the reaction mixture andfrom which the sulfur-trioxide-free and/or sulfur-trioxide-poor inertgas stream is drawn off.

The second one of thesetwo processes is described in co-pendingapplication Serial No. 194,786 filed the same day herewith. According tothis process, the sulfur-trioxide necessary'for the sulfonation isdissolved in the starting materials to be sulfonated at temperatureswhich are not yet sufficient for a practically complete sulfonation,and-only then the temperature is gradually brought to the heightnecessary for a complete sulfonation. The dissolving of thesulfur-trioxide appropriately occurs at temperatures within the range of10-45 and preferably of 20-35 C., i.e. at temperatures at which thesulfonation For the obtaining of high.

does not proceed or proceeds comparatively slowly. Then,

the temperature is gradually raised so that the sulfonation proceedswith technically serviceable speed, but not tocompletion, as for exampleto up to 70 and preferably up to 65 C. If there is obtained at thesetemperatures, up to 70C., a degree of sulfonation of at least 50% andpreferably of 60-80%, then the sulfonation is completed by raising thetemperature to at most 100 C. and preferably 75-95 and most preferably-90 C.

The sulfonation products always contain excess quantities ofsulfur-trioxide, which may be removed according to the process ofco-pending application Serial No. 194,-

83 8, filed the same day herewith, now abandoned, by converting themwith such substances, containing aliphatic hydroxyl groups, whosesulfatization products possess surface-active properties. These hydroxyhydrocarbon compounds contain as hydrophobic radical a hydrocarbonradical with 10-28 and preferably 12-18 carbon atoms, wherein in thecase of alkyl-aromatic or cyclo-alkyl-aromatic radicals at least 8 ofthese carbon atoms must be of aliphatic or cyclo-aliphat-ic nature.Examples for such hydroxy hydrocarbon compounds are fat-alcohols orfatty acid alkylol amides or water-insoluble or water-soluble partialethers or partial esters of fat alcohols, alkyl-phenols or fatty acidswith polyvalent alcohols, wherein the partial ethers may be, in. theform of the addition products of ethylene oxide and/or propylene oxideto fat alcohols, alkyl phenols, acyl-phenols, fatty-acid amides or fattyacid alkylol amides or fatty acids.

If one converts the excess sulfur-trioxide present in the sulfonationproducts with these hydroxy hydrocarbon compounds forming surface-activesubstances, then it is possible to use in the sulfonation substantiallylarger quantities of sulfur-trioxide, for example, up to 2 or 3 molsulfur-trioxide per mol fatty acid radical. This manner of working hasthe advantage that it is possible to obtain, with sulfonationtemperatures below 70 C., high degrees of sulfonation.

In the conversion of sulfur-trioxide with fatty acids and/or theirderivatives, the formation of colored impurities may not be entirelyavoided even when using the above-mentioned processes. Therefore, it maybe appropriate to bleach these products. Thus, it may be effected.according to copending application Serial No. 194,998, filed the sameday herewith, now US. Patent 3,159,657, using 0.2-6 weight percent,preferably l-4 weight percent hydrogen peroxide, calculated as 100%product. If starting materials are processed which do not contain anyimpurities or accompanying substances, forming colored decompositionproducts in the sulfonation, then in general less than 4% and preferablyless than 3% peroxide may be used. The hydrogen peroxide is chargedpreferably as 20-75 weight percent and most preferably as 30-50 weightpercent-product. Furthermore, it is advisable, to thus choose theconcentration of the hydrogen peroxide to be used in dependence on itsquantity so that the sulfuric acid forming at the start of the bleachingprocess from free sulfur-trioxide and the Water quantity introduced withthe hydrogen-peroxide, is not more diluted than a 20% sulfuric-acid,Preferably this sulfuric acid is to represent, mathematicallyconsidered, a mixture of sulfur-trioxide and water with asulfur-trioxide-con-tent up to 95 weight percent and preferably up to-95 weight percent. The bleaching occurs at temperatures within therange of 20-100 and preferably of 40-80 C.

The bleaching of the sulfonation products may take place immediatelysubsequent to the sulfonation, or subsequent to the conversion of theexcess sulfur-trioxide with hydroxy hydrocarbon compounds whereprovided. However, if the excess sulfonation agent is. converted afterthe bleaching with added hydroxy hydrocarbon compounds, then it isadvisable to adjust quantity and concentration of the hydrogen peroxidein dependence on the sulfur-trioxide-content of the reaction product sothat the mixture of 'sulfur-trioxide and water, present in the reactionproduct (mathematically considered), corresponds at least to a 98%sulfuric acid. One may keep the water content so low that this mixture,mathematically considered, consists up to 95 weight percent andpreferably of 80-90 weight percent of sulfur-trioxide.

A conversion of the excess sulfonation agent with the added hydroxyhydrocarbon compound, carried out after the bleaching, is above all mosttechnically interesting, in the processing of sulfonation productscontaining fatty acids which are to be esterified with the addedhydroxyl compound, or if one simultaneously Wishes to re-esterify thesulfonated fatty acid esters.

The neutralization of the instant mixture of sulfonate and sulfuric acidester with inorganic or organic bases takes place in the customarymanner. If starting materials containing fatty acids have beensulfonated, then the preferably bleached sulfonic acids may be soneutralized that the sulfo-fatty-acids are present as mono-salts, whichthen are esterified in a manner known per se with addedhydroxyl-compounds.

In the following examples, given by way of illustration and notlimitation, the triglycerides processed have been treated for theremoval of slime and subjected to deacidification and hardening. Theiodine number of the hardened tallow amounts to 0, that of the hardenedcoconut oil amounts to 1. The fatty acid esters processed arepractically saturated (iodine number not greater than 0.2) and have beenpurified through distillation.

In the case of the triglycerides, the anal-indications refer to thefatty acid radicals. In all cases the sulfonation products obtained atthe end of the sulfonation were still well fluid and no difiicultieswhatsoever were encountered. In the sulfonation of triglycerides,however, without the additions in accordance with the invention, theviscosity of the reaction mixture rapidly increases and great quantitiesof a very stable foam form. Also a uniform working-in of the hydrogenperoxide into the sulfonation product cooled to temperatures below 50 C.is very difiicult.

Example 1 Into a mixture of 61 g. hardened coconut-oil (0.25 mol) and 63g. of the ethylester of a hardened palmkernel-fatty-acid (0.25 mol) 52g. sulfur-trioxide gas (0.65 mol), diluted with 20-fold volume-quantityof air, was introduced in the course of 60 minutes at 80 C. After theintroduction, the mixture. still remained standing for about 15 minutesat 89 C. The crude acid sulfonation product was bleached with 3% of itsweight of H (as 40% aqueous solution) for 30 minutes at 60 C., and thenneutralized with 5%-soda-lye. The degree of sulfonation of the, productwas 96.4%. 5%-solution of the sulfonate, with reference to crude acidsulfonation product, showed in the Lovibond-Tintometer in a 4" cell,the, following color values:

Yellow: 4.6; red: 0.4; blue: 0.1

Example 2 A mixture of 72 g. hydrogenated tallow (melting point 57.5 C;0.25 mol) and 62 g. of the ethylester of a hydrogenatedpalm-kernel-fatty acid (0.25 mol), mentioned in Example 1, was, asdescribed in Example 1, sulfonated, bleached and neutralized. The degreeof sulfonation of the product amounted to 98.5%; the Lovibond colorvalues were:

Yellow: 1.4; red: 0.3; blue: 0.0

Example 3 A mixture of 83 g. hardened coconut-oil (0.375 mol) and 31 g.ethylester of a hardened palm-kernel-fattyacid (0.125 mol) was, asdescribed in Example 1, sulfonated, bleached, and neutralized. Thedegree of sulg donation of the product amounted to 79.1%; the colorvalues measured in the Lovibond-Tintometer in a 4" cell were:

Yellow: 2.3; red: 0.6; blue: 0.4

Example 4 A mixture of 63 g. of the ethylester of a hardenedpalm-kernel-fatty-acid (0.25 mol), 37 g. of the ethylester-of a hardenedtallow fatty-acid (0.125 mol) and 28 g. of a hardened coconut-oil (0.125mol) was, as described in Example 1, sulfonated, bleached andneutralized. The degree of sulfonation of the product amounted to 96.1%the color values measuredin the Lovibond- Tintometer in a 4" cell were:

Yellow: 1.0; red: 0.1; blue: 0.0

0 Example 5 I A mixture of 60 g. of the methyl-ester of a hardenedpalm-kernel-fatty-acid (0.25 mol), 36 g. of the methylester of ahardened tallow-fatty-acid (0.125 mol) and 28 g. hardened coconut-oil(0.125 mol) was, as described in Example 1, sulfonated, bleached andneutralized. The degree of sulfonation of the product amounted to 97.4%the color values measured in the Lovibond-Tintometer in a 4" cell were:

Yellow: 2.1; red: 0.5; blue 0.0

Example 6 For the carrying-out of the test here described, 5 of thevessels 13 shown in the drawing, were connected one after the other, inseries. The starting m-ateriahto be sulfonated is designated 3 and thelines 14 and 15 provided with the valves 16 and 17, are for theintroduction of the starting material to be sulfonated and thesulfurtrioxide-air mixture. 19 is an outlet for air, substantially freefrom sulfur-trioxide, and 18 an outlet for the reaction mixture. Thelower part of the reaction vessel is surrounded by the heat jacket 6with the heat exchange inlet 7 and outlet 8.

As starting material, a mixture of 2500 g. ethylester of a hardenedcoconut-oil-acid and 2200 g. hardened coconut-oil was used.

At the start of the test, the first four reaction vessels were filledwith ester and the heating adjusted so that the reaction mixture in thevessels had during the entire test the following temperatures, risingfrom vessel to vessel: 1st vessel, 50; second vessel, 60, 3rd vessel 70,4th vessel, 80, 5th vessel C. Sulfur-trioxide, diluted with a 20- foldvolume quantity of air, was blown into the first four vessels in suchquantities that in the individual vessels, the followingsulfur-trioxide-quantities- (indicated in percent of thestoichiometrically necessary quantity for a quantitative sulfonation)were taken up 1St-'52, 2nd 78, 3rd104, 4thl30%. No sulfur trioxide wasblown into the last vessel. After these quantities had been taken up,the processes were eflFected in continuous operation, and the firstvessel was fed with 118 g. of the starting material per hour.Simultaneously, so much sulfur-trioxideair-mixture was introduced intothe first four reaction vessels that the above indicated sulfur-trioxidequantities had been supplied to the material leaving the individualvessels. No sulfur-trioxide, however, was blown into the last vessel asthis vessel served for the afterreacting. The product running off fromthe apparatus was cooled and bleached with 2% of its weight H 0 (as 40%aqueous-solution) for 2 hours at 5560 C. and subsequently neutralizedwith 10% soda-lye. The degree of sulfonation of the product was thecolor values, measured in the Lovibond-Tintorneter in a 4" cell were:

Yellow: 9.0; red: 2.0; 'blue: 0.0

Example 7 The sulfonation was effected in an apparatus according to FIG.2. This device consists of an absorption vessel 7 20 and the heatexchange device 40, which are connected with one another through theline 30. The absorptionvessel 20 consists of an interior vessel 21,which is surrounded by a heating jacket 22 with feed-line 23 anddischarge-line 24 for the heat exchange liquid. The starting material isintroduced through the nozzle 27, while the sulfur-trioxide-inertgas-mixture is conducted through the line 25 under the surface of thestarting material in the vessel 21. The inert-gas, practically free fromsulfur trioxide, passes out at 26; the temperature is indicated'on thethermometer 28, which also may be developed as thermo-regulating device,such as a thermostat which controls the flow of the heat exchangeliquid.

At the bottom of the absorption-vessel, the starting material,containing sulfur-trioxide, is drawn-01f through the line 30, which maybe shut-off through the stop-cocks 31 and 32 as against the absorptionvessel and/or the heat exchange device. The, line 30 is bent upward in aU-shape and thus fulfills the function of a level-regulator. At thehighest place, the deaerating-device 33 is mounted, while at the lowestpoint, shortly before the heat exchange device, is the discharge faucet34.

The heat exchange device is developed as a coil 41 I provided with thejacket 42 with the heat exchange agent- (iodine number=0.5) and 1500 g.(6 mol) of the ethyl-.

ester of a hardened coconut-oil-acid.

(iodine number=0.3)

was used. Into about 1 mol (referred to fatty-acid-r-adicals) of thismixture, in the interior vessel 21 of the absorption-device 20, wereblown-in in the course of about 2 hours at 30 C., 1.3 molsulfur-trioxide, diluted with a 20-fold air quantity. After thisquantity was dissolved, the sulfonation was continued as a continuousoperation by adding per hour so much ester that the median time of stayof the ester in the absorption vessel amounted to 2 hours. Thesulfur-trioxide was added continuously in a quantity of 1.3 mol per molof fed fattyacid-radicals. The three heat exchange coils, connectedbehind the absorption vessel, were held at temperatures of 60, 80 andp90C. The time of stay in each coil amounted to about 20 minutes. Thematerial had, upon passing out of the first reaction coil, a degree ofsulfonation of about 65-70%.

The product passing out of the last reaction coil was cooled, thenbleached with 2% of its weight of H (used as 40%-aqueous-solution) for 2hours at 50-60 C., and neutralized with l0%-soda-lye. The degree ofsulfonation of the product amounted to 94-95%. The Lovibond color valuesof the bleached product, measured as a- %-solution of the sulfonate,with reference to crude acid sulfonation product, in a 4" cell, were:

Yellow: 18; red: 2.5; blue: 0.0

Example 8 Into a mixture of 53 g. (0.25 mol) of the ethylester of ahydrogenated palm-kernel-fatty acid (iodine number=0.3) and 56 g. (0.25mol referred to fatty-acidradicals) of a hydrogenated coconut-oil(iodine number=0.4), 52 g. (0.65 mol) sulfur-trioxide, diluted with20-fold quantity of air, were introduced in the course'of 15 minutes attemperatures of 30-40 C. The product thus obtained was heated in thecourse of minutes to 70 C., where a degree of sulfonation of about 65%had been reached, and then the temperature was raised in the course offurther 5 minutes to 80 C. after the product had been held for 45minutes at this temperature, it was bleached for 8 hours at 3040 C. with2% of its weight of H 0 (as 40%-aqueous-solution) and neutralized with8%-soda-lye. The Lovibond color values of a 5% solution of thesulfonate, in reference to crude acid sulfonation product, amounted,measured in a 4" cell, to:

Yellow: 4.1; red: 0.7; blue; 0.0

with an excess of gaseous S0 the improvement which comprises effectingthe sulfonation with the ester in admixture with about 20 to 85% byweight of an ester of a fatty acid having from 6-28 carbon atoms with amonovalent alcohol.

2. Improvement according to claim 1 in whichsaid sulfonation is effectedwith said ester of the polyvalent alcohol in admixture with about 20-75%by weight of said ester of the monovalent alcohol.

3. Improvement according to claim lin which said ester of a monovalentalcohol is an ester of a lower monovalent alcohol.

4. Improvement according to claim 1 in which said ester of saidpolyvalent alcohol and said ester of said monovalent alcohol arepurified materials having an iodine number below 5.

5. Improvement according to claim 1 in which said ester of, saidpolyvalent alcohol and said ester of said monovalent alcohol arepurified materials having an iodine number below 2.

6. Improvement according to claim 1 in which said sulfonation iseffected in a multiple number of sulfonation steps with the startingmixture being initially contacted in the first sulfonation step at atemperature below 70 C. with from 60% to 90% of the sulfur dioxidequantity and in which the mixture. is thereafter contacted in thesubsequent sulfonation step at a temperature between about 75-95 C. withthe remaining sulfur trioxide.

7. Improvement according to claim 1 in which the sulfonation isetfectedby initially dissolving the sulfur trioxide in the reactionmixture at a temperature between about-'1045 C., and thereafterincreasing the temperature to a value not in excess of about 70 C.

triglycerides containing a substantially saturated unsubstituted fattyacid radicalhaving from 6-28 carbon atoms in which the triglyceride isreacted with an excess of a gaseous S0 the improvement which compriseseffecting the sulfonation with the triglyceride in admixture with about20 to' by weight of an ester of a fatty acid having from 6-28 carbonatoms with a monovalent alcohol.

11. Improvement according to claim 10 in which said ester of said fattyacid with said monovalent alcohol is present in amount of about 20-75%by weight.

12. In the process for the sulfonation of fatty acid triglycerides whichcontain a substantially saturated unsubstituted fatty acid radicalhaving from 6-28. carbon atoms in which the triglyceride is reacted withan excess of 9 gaseous S the improvement which comprises efiecting thesulfonation with the triglyceride in admixture with about 20-85% byweight of a member selected from the group consisting of fatty acidmethyl and fatty acid ethyl esters containing from 628 carbon atoms inthe fatty acid radical.

13. Improvement according to claim 12 in which said group member ispresent in amount of about -75% by weight.

14. Improvement according to claim 13 in which said sulfonation iseifected at a temperature between about and C. using sulfur trioxidediluted in an inert gas stream.

References Cited by the Examiner UNITED STATES PATENTS 1,926,442 9/1933Gunther et a1 260400 2,691,040 10/ 1954 Bloch et a1 260-400 2,878,2713/1954 Little et a1. 260400 FOREIGN PATENTS 617,347 8/ 1935 Germany.288,126 '4/ 1929 Great Britain.

CHARLES B. PARKER, Primary Examiner.

DANIEL D. HORWITZ, Examiner.

1. IN THE PROCESS FOR THE SULFONATION OF FATTY ACID ESTERS OF POLYVALENTALCHOHOLS WHICH CONTAIN A SUBSTANTIALLY SATURATED UNSUBSTITUTED FATTYACID RADICAL HAVING FROM 6-28 CARBON ATOMS, IN WHICH THE ESTER ISREACTED WITH AN EXCESS OF GASEOUS SO2, THE IMPROVEMENT WHICH COMPRISESEFFECTING THE SULFONATION WITH THE ESTER IN ADMIXTURE WITH ABOUT 20 TO85% BY WEIGHT OF AN ESTER OF A FATTY ACID HAVING FROM 6-28 CARBON ATOMSWITH A MONOVALENT ALCOHOL.